On Wednesday 24 March 2010 22:34:59 Andrew Dyer wrote: > >> What is the purpose of CONFIG_PCI_BOOTDELAY? I am using uboot version > > > > Adding a delay so the PCI controllers can come up and stabilize. > > > >> Specifically in my case, all the resets on my board have occurred well > >> before (500 msec) this portion of the code would execute, so it would > >> seem safe to say that any peripherals like PCI controllers would be > >> satisfied reset-wise. > > > > 500ms is not safe. We have seen cases (for example on 440SP / 440SPe) > > where 5...10 seconds (!) were needed. > > I've seen this as well, so I agree that 500ms seems reasonable for a > general value. Per the PCI 2.3 spec, the time is supposed to be min. > 100mS.
Per PCI 2.2, the PCI target must respond to config accesses within 2^25 clock cycles after #RST is de-asserted (PCI System Architecture, fourth edition, page 321). With 33MHz this is approx. 1 second. Cheers, Stefan -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-0 Fax: (+49)-8142-66989-80 Email: [email protected] _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
